[Bug rtl-optimization/115877] [15 Regression] wrong code at -Os (missing zero extension)

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115877

--- Comment #2 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Fairly sure the root cause is the TImode assignments.  Based on what I'm
seeing, we may have a problem with vectors as well -- worth keeping mind if
there's additional bug reports against ext-dce.